The present invention relates to a machine for receiving elongated products mutually attached end to end to form a continuous string of products and performing a manufacturing operation with one or more of the individual products, and more particularly to a feed mechanism for incrementally feeding the string of products.
Machines for handling continuous strips of elongated products that are mutually attached end to end must be able to intermittently engage and advance each individual product into precise alignment for performing some manufacturing operation without regard to tolerance buildup caused by dimensional variations of the individual pieces of the strip. Typical examples of elongated products that are mutually attached end to end are square wire pins, shown in FIG. 1, and round wire pins, shown in FIG. 2. While the teachings of the present invention can be advantageously applied to the manufacture and use of other elongated products, for simplicity and to promote a more clear and better understanding of the present invention the following description of the invention will be limited to the elongated products shown in FIGS. 1 and 2. However, it is intended that the scope of the invention will include other elongated products as well. There is show in FIG. 1 a strip 10 of individual elongated pins 12, adjacent pins of which are interconnected or attached end to end at indentations 14. The strip 10 of pins is made of square wire so that the pins 12 have a square cross section. Each indentation includes angled surfaces 16 and 18 that are formed on the two adjacent pins, as shown. Similarly, there is shown in FIG. 2 a strip 20 of individual elongated pins 22, adjacent pins of which are interconnected or attached end to end at indentations 24. The strip 20 of pins is made of round wire so that the pins 22 have a round cross section. Each indentation includes angled surfaces 26 and 28 that are formed on the two adjacent pins, as shown. A portion 40 of a prior art feed mechanism is shown in FIG. 3, and includes a block 42 having a track 44 formed therethrough containing and guiding a strip 10 of pins 12. A feed pawl 46 is pivotally attached within a cutout 48 in the block by means of a pivot pin 50. The feed pawl 46 is urged by a spring 52 to pivot clockwise, as viewed in FIG. 3, so that a point 54 engages an indentation 14 of the strip 10, as shown. As the block is moved in the feed direction indicated by the arrow 56, by a mechanism not shown, the point 54 is pressed firmly into the indentation forcing the strip 10 against the opposite wall of the track 44 so that the strip 10 must move along with the block. After the end of the feed stroke is reached the strip 10 is held in place, by a mechanism not shown, while the block is moved in the return direction indicated by the arrow 58. This movement requires that the point 54 cam out of the indentation 14 and ride along the outer surface of the pin 12 until it reaches the next upper indentation, when the feeding process can be repeated. However, a potential problem arises in that, as the point 54 rides along the surface of the pin 12 it may scratch or otherwise mar the pin. Another potential problem with this prior art mechanism is that the block necessarily moves through a fixed distance in its feed and return strokes. In the event that the longitudinal spacing of the indentations 14 varies or is slightly different than the fixed movement of the block 42, the amount of the variation can accumulate to the point where it exceeds the length of the indentation. This occurs because at the top of each return stroke the point 54 will engage the angled surface 16 wherever it happen to be and then will feed the strip from that position a fixed amount and then will return to the next indentation, which may be slightly further away than the fixed return stroke anticipates. So that each cycle causes the point 54 of the pawl 46 to engage the angled surface 16 further and further away from the center of the indentation 14. Eventually, the point 54 will no longer engage an indentation 14 and the feed mechanism will malfunction.
What is needed is a feed mechanism that will feed a strip of elongated products without the possibility of scratching or marring the outer surface of the product, and that will accurately feed a strip of elongated products having variations in the spacing of the indentations and wherein the spacing may be slightly different than the fixed stroke of the feed mechanism.
A machine is provided for receiving a continuous strip of elongated products mutually attached end to end. The machine includes a frame and is arranged for incrementally feeding the strip of products and performing a manufacturing operation therewith. Each two adjacent products are attached at an indentation. A feed mechanism is coupled to the frame of the machine for incrementally feeding the strip of products. The feed mechanism includes a feed track for closely receiving and guiding the strip of products along a first axis, and first and second feed fingers mutually opposed on opposite sides of the first axis. Means is provided for moving the first and second feed fingers toward the first axis until in feeding engagement with the strip of products without gripping the strip of products. Additionally, an actuator is included for moving the first and second feed fingers in a direction parallel to the first axis thereby feeding the strip of products along the first axis.
The feed mechanism further includes a drive carriage and a follower carriage coupled to the frame and arranged for independent sliding movement along the first axis. The feed track extends along the first axis through both the drive carriage and follower carriage. The first and second feed fingers are carried by the drive carriage and coupled to the follower carriage so that relative motion of the drive carriage toward the follower carriage in the feed direction causes the feed fingers to mutually move into feeding engagement with the strip of products for effecting the incremental feeding thereof without gripping the strip of products;
An embodiment of the invention will now be described by way of example with reference to the following drawings.